Obese Grizzly Bears Shed Light on Diabetes Research

Grizzly bears are offering some surprising insights into diabetes research. These massive mammals are obese in the autumn and then become diabetic weeks later during hibernation. Yet after they fully wake in the spring, grizzly bears are somehow "cured" of their diabetes.

In humans with type 2 diabetes, cells lose the ability to respond to insulin. This hormone helps regulate the level of sugar in the body. In grizzly bears, though, the insulin levels in the animals' blood do not change. Instead, the cells that insulin communicates with turn on and off their ability to respond to insulin.

In fact, the researchers found that when grizzlies are more obese, they are also more insulin sensitive. This means that they're less diabetic. They manage this feat by shutting down the activity of a protein called PTEN in fat cells. In addition, grizzlies manage store all of their fat in fat tissue rather than in the liver and muscle, which are common places for fat to accumulate in other animals with obesity.

"This is in contrast to the common notion that obesity leads to diabetes in humans," said Kevin Corbit, one of the researchers, in a news release. "Our results clearly and convincingly add to an emerging paradigm where diabetes and obesity-in contrast to the prevailing notion that the two always go hand-in-hand-may exist naturally on opposite ends of the metabolic spectrum."

In fact, the new researcher hints that the cellular mechanisms leading to obesity in certain patients may actually be the same mechanisms that could be protecting them from diabetes. In addition, the same mechanisms in other patients may also be what protect them from becoming obese.

"Moving forward, this more sophisticated understanding of the relationship between diabetes and obesity should enable researchers not only to develop therapies targeting these mechanisms, but also to identify the appropriate patients to whom these therapies should be targeted," said Corbit.

The findings are published in the journal Cell Metabolism.